The Cell Sorter Core will provide expertise in marrow or skin stem cell separations and analysis of donor cells in cell suspensions. The core will be headed by Dr. Nicola Kouttab. Dr. Koutab runs the flow facility at RWMC and has experienced technicians. In addition, Mr Marc Dooner is an experienced stem cell/Sorter technician and will devote 15% time to this Core. The other technicians working with Dr. Koutab will be able to provide backup and cross coverage although they are not a formal component of the Core. We have made a decision to hire an accomplished full time technician solely dedicated to this COBRE, since this is justified by the complexity and extent of the proposed work. This core features a new MoFIo highspeed cell sorter from Cytomation. This sorter is capable of carrying out stem cell separations, single cell deposition and large event analysis. This core is housed in a dedicated, newly renovated room within an established flow cytometry facility. This FACS facility is equipped with a FACS scan and a FACS calibur (BD instruments). Both machines can act as a backup for any analysis work required by the projects. Investigators will work with the core and prepare their cell populations for sorting or analysis. The core will routinely separate Lin- Rho(lo)Ho(lo),Lin - Hoechst side populations and Lin - Sca+ CD45- cells and analyze populations for GFP+ or CFDA-SE positive cells. The core will serve all projects in this COBRE carrying out both separations and analysis work for projects 1, 2, 3. The core also remains dedicated to the development of new and the enhancement of already known stem cell separations.